Assessment of Plant Failure in High Winds

• Main Authors: Chung-Yi Li, 李昌益
• Other Authors: Tsang-Jung Chang
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/48801870348595615142

碩士 === 國立臺灣大學 === 農業工程學研究所 === 89 === A theoretical model, based on two masses system, for the lodging of plants is developed, from herbaceous to woody plants, for dynamic assessment of plant failure in high winds. The model is first used to investigate the behavior of isolated plants in high winds by calculating base bending moments. The result is then used in stem base and root failure criteria to estimate failure wind speeds. The plants and soil parameters are of great importance in lodging process, including the plant’s ear area, shoot’s centre of gravity height, dry natural frequency, plant’s shoot number, stem base radius, wall thickness, failure yield stress, root plate diameter, structural rooting depth, soil characteristic and root-soil plate mass. The meteorological factors influencing lodging are wind speeds and rainfalls. The simulated results relative error is in 10.4±6.6％ with the published experimental data of rices in wind tunnels. The present research further conducts a series of assessment for various plants. It is concluded that the failure wind speeds for wheat and rice are 21 ms-1 and 18 ms-1, respectively. The failure wind speeds for plane trees in leaf and out of leaf are 15 ms-1 and 33 ms-1, respectively, and pines in leaf and out of leaf are 14 ms-1 and 27 ms-1, respectively. The stem bending moment of rice is higher than that of wheat because the rice stem is more sturdy. However, the root failure of rice may occur since the higher soil water content in rice field causes the soil shearing stress to be reduced.